"The policy they are pursuing is dangerous not only for regional peace but for European peace," Willy Wimmer said.
Wimmer, who was a state secretary in the German Defense Ministry between 1988 and 1992, said Ankara was "not in a position" to drag NATO into a war, but stressed the military bloc would be better off without Turkey.
"We cannot allow Turkey to make use of NATO facilities to create a disastrous situation for all us, therefore it would be better not to have Turkey in the alliance," he said.
Last week, the Russian Defense Ministry presented satellite images suggesting Turkey was buying smuggled oil from IS militants. Ankara has denied the claim.
The views and opinions expressed in the article do not necessarily reflect those of Sputnik.